1. Field of the Invention
The invention relates to a pipe coupling with a fitting and with a cylindrical pipe, whose smooth end section can be inserted into and pressed together with a fitting.
2. Discussion of the Prior Art
Pressed pipe couplings are offered by various manufacturers (Mannesmann, Seppelfricke, Viegener, etc.). The systems provided by these manufacturers have in common that a sealing ring is arranged between the inserted pipe end and the outer fitting. For this purpose, the fittings have one or two (Seppelfricke Co.) outward bulges, in which the sealing ring is arranged. During pressing, this bulge area and an adjacent cylindrical area are pressed simultaneously. In addition, there are systems offered by other manufacturers (Fraenkische Rohrwerke, Geberit, Roth, Unipipe, etc.) that operate with an inner fitting. Most of the aforementioned manufacturers use a composite pipe, specifically, a so-called three-layer pipe, in which an aluminum pipe with a welded longitudinal seam is arranged so as to form a diffusion block between a thick-walled inner pipe of PE and a thick-walled outer sleeve of PE-HD. In some of the cases in which composite pipes are used (e.g., Fraenkische Rohrwerke and Unipipe), pressing is carried out by means of a pressing sleeve placed externally onto the composite pipe. In contrast, the Roth Co. uses a plastic pipe, into which a support body can be inserted to provide support.
It is disadvantageous in the above solutions with an inner fitting that the conduit cross-section is reduced. Moreover, turbulence is created in the flow at the discontinuous transitions between the inner fitting and the pipe, increasing the flow resistance. It is disadvantageous in the solutions with an outer fitting that, once the pipe has been inserted into the fitting, it is not possible to determine from the outside whether the pipe has reached the prescribed insertion depth.
A generic pipe coupling is disclosed in German Reference DE 43 29 442 A1. This pipe coupling has an elongated metal sleeve that forms a fitting, into which are inserted the two pipes to be connected, which are of equal diameter. The metal sleeve, which has a diameter somewhat larger than that of the pipes, is beaded in the edge areas in such a way that the sleeve edges rest on the pipe walls without any gaps. The space between the sleeve and the pipe walls is filled by a rubber collar placed into the sleeve in a secure manner. After insertion of the pipes, crimps are pressed into the sleeve wall with such pressure as to form crimps of equal area in the pipe walls. In this system, it is disadvantageous that the wide pressing jaw requires a great deal of space, so that pressing cannot be carried out in close quarters. In addition, an extension is needed for most of the fittings, particularly in the case of T-pieces, so that the pressing clamps can be applied. Moreover, the aforementioned problem in systems with an outer fitting occurs in this system as well, i.e., the insertion depth cannot be checked for correctness.
In FR 2398955, FIG. 6, a pressed pipe coupling is disclosed, in which a metal sleeve, which penetrates an elongated sealing element in the form of a bushing, is arranged in the pressing area between the outer wall of a smooth-ended pipe and the inner wall of the widened end area of a pipe to be connected. The metal sleeve, at one end, has a collar, which preferably is connected to the end face of the smooth-ended pipe by welding. This known design has the disadvantage of being suitable only for large pipeline pipes. Moreover, expansion of the end area of the pipe to be connection is required. Further, the fixing in place of the metal sleeve on the end face of the smooth-ended pipe by welding acts contrary to the pressing method, which has been developed to make welding and soldering unnecessary.